A subdural hematoma is a type of intracranial hematoma (blood clot or clots) that often results from a skull fracture.

Causes

When there is a direct blow to the head, the bruising of the brain and the damage to the internal tissue and blood vessels is due to a mechanism called coup-countercoup. A bruise directly related to trauma, at the site of impact, is called a coup lesion (pronounced COO). As the brain jolts backwards, it can hit the skull on the opposite side and cause a bruise called a countercoup lesion. The jarring of the brain against the sides of the skull can cause shearing (tearing) of the internal lining, tissues, and blood vessels that may cause internal bleeding, bruising, or swelling of the brain.

A subdural hematoma occurs when a blood clot forms underneath the skull and underneath the dura (the tough covering that surrounds the brain) but outside of the brain. These can form from a tear in the veins that go from the brain to the dura, or from a cut on the brain itself. They are sometimes, but not always, associated with a skull fracture.

Symptoms

Patients with this type of condition frequently have bruises around their eyes and a bruise behind their ear. They may also have clear fluid draining from their nose or ears due to a tear in part of the covering of the brain. These patients usually require close observation in the hospital.

The person may have varying degrees of symptoms associated with the severity of the head injury. The following are the most common symptoms of a head injury. However, each individual may experience symptoms differently. With this type of moderate to severe head injury, immediate medical attention is required. Symptoms may include:

• confusion
• loss of consciousness
• blurred vision
• severe headache
• vomiting
• loss of short-term memory, such as difficulty remembering the events that lead right up to and through the traumatic event
• slurred speech
• difficult walking
• dizziness
• weakness in one side or area of the body
• sweating
• pale skin color
• seizures
• behavior changes including irritability
• blood or clear fluid draining from the ears or nose
• one pupil (dark area in the center of the eye) looks larger than the other eye
• deep cut or laceration in the scalp
• open wound in the head
• foreign object penetrating the head

The symptoms of a head injury may resemble other problems or medical conditions. Always consult your physician for a diagnosis.

Diagnosis

The full extent of the problem may not be completely understood immediately after the injury, but may be revealed with a comprehensive medical evaluation and diagnostic testing. The diagnosis of a head injury is made with a physical examination and diagnostic tests. During the examination, the physician obtains a complete medical history of the patient and family and asks how the injury occurred. Trauma to the head can cause neurological problems and may require further medical follow up. Diagnostic tests may include:

• Blood tests
• X-ray — a diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
• Computed tomography scan (Also called a CT or CAT scan.) — a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.
• Electroencephalogram (EEG) — a procedure that records the brain's continuous, electrical activity by means of electrodes attached to the scalp.
• Magnetic resonance imaging (MRI) — a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.

Treatment

Treatment is individualized, depending on the extent of the condition and the presence of other injuries. Depending on the severity of the injury, treatment may include:

• Observation
• Immediate medical attention
• Stitches
• Hospitalization for observation
• Surgery

Head injury may cause the brain to swell. Since the brain is covered by the skull, there is only a small amount of room for it to swell. This causes pressure inside the skull to increase, which can lead to brain damage. If the patient has a severe head injury, he/she may require monitoring for increased intracranial pressure (ICP) (pressure inside the skull).

How is ICP monitored?

Intracranial pressure is measured in two ways. One way is to place a small hollow tube (catheter) into the fluid-filled space in the brain (ventricle). Other times, a small, hollow device (bolt) is placed through the skull into the space just between the skull and the brain. Both devices are inserted by the physician either in the intensive care unit (ICU) or in the operating room. The ICP device is then attached to a monitor that gives a constant reading of the pressure inside the skull. If the pressure goes up, it can be treated right away. While the ICP device is in place, the patient will be given medication to stay comfortable. When the swelling has gone down and there is little chance of more swelling, the device will be removed.